The present invention relates to a liquid filter for removing contaminants from a liquid such as lubricating oil, water or fuel.
An oil filter for filtering lubricating oil is known from German Patent 43 03 695 in which a cover, onto which an annular filter insert which separates the outer feed chamber from the inner discharge chamber is removably attached, is screwed on to the filter housing, which is positioned substantially vertically, of the oil filter for filtering lubricant oil. A valve-like element, which opens automatically every time the filter insert is changed and is used to drain the oil remaining in the filter housing via a drain channel to an oil collection chamber, is provided in the lower region of the filter housing.
A central rod is connected to the cover so it is rotatable and axially movable in a limited way. In its region near the cover, the central rod has a piston-like enlargement, which is sealed relative to the filter insert and separates the feed chamber from the discharge chamber. The central rod includes the valve-like element, which works together with the drain channel, in its lower end region.
The length of the central rod, which reaches from the cover through the oil filter to the drain channel in the floor of the filter housing, is disadvantageous in this embodiment. When the filter is replaced, the cover is unscrewed from the filter housing and must be pulled upward in the axial direction until the central rod is removed from the filter housing. A substantial maintenance height is necessary for this purpose. After the cover having the central rod and the filter insert is pulled out of the filter housing, the used filter insert must be removed from the cover. For this purpose, the soiled filter insert must be pulled off over the long central rod and the new filter insert must be pushed onto the long central rod in turn, while the central rod is able to move at an angle to the cover in the region of its snap connection to the cover. Furthermore, there is the danger that the long central rod or its gaskets could be damaged while the filter is replaced.
The object of the present invention is to avoid the disadvantages cited above.
This object is achieved by the invention as described and claimed hereinafter.
The liquid filter according to the present invention comprises a filter housing, a filter element, a support body for the filter element, and a slide valve. It is used to filter a liquid such as lubricant oil of an internal combustion engine, water, or fuel. The filter housing comprises a housing body and a housing cover, the housing cover being connected to the housing body to form a seal. In this case, sealing means which are inserted between the housing cover and the housing body may be provided. The housing parts (housing cover and housing body) are detachably connected to one another. An advantageous embodiment is to screw the housing parts together. An unfiltered liquid inlet, a filtered liquid outlet, and an unpressurized filter outlet are arranged in the filter housing, particularly in the housing body. The unfiltered liquid inlet is separated by the filter element from the filtered liquid outlet, which forms a seal between them. The filter element is designed in such a way that it defines a filter interior space. The filter interior space may be made cylindrical or in the form of a rectangular solid, for example, and has two opposing openings. A support body is positioned in the filter interior space, supporting the filter element through which the liquid flows from the outside to the inside. The support body may be fixedly connected to the filter element or loosely inserted into the filter element, for example.
The filter outlet is closed by a slide valve, which is connected to the housing cover via an intermediate element, such as a connecting member or the support body, so they correspond. When the filter element has to be replaced, the housing cover is lifted off of the housing body, as a result of which the slide valve is moved axially and opens the unpressurized filter outlet. The liquid in the filtered liquid area of the liquid filter may drain out through the liquid outlet. Furthermore, the filter outlet may be correspondingly connected to the unfiltered liquid inlet such that this connection advantageously can also be established or interrupted by the slide valve. Therefore, in an advantageous embodiment of the liquid filter, the unfiltered liquid may drain into the liquid outlet before the filtered liquid reaches the liquid outlet, as a result of which no unfiltered liquid reaches the filtered side even during filter replacement, and therefore no contaminant particles may accumulate in the filtered liquid area.
In a first variant, the slide valve may be detachably connected to the support body. The support body is correspondingly connected to the housing cover and is inserted into the filter element. In this case, the support body may be detachably or permanently connected to the housing cover, for example. However, if there is a detachable connection between the housing cover and the support body, this connection has to be able to withstand greater axial forces than the detachable connection between the support body and the slide valve.
In a second variant, the slide valve is detachably connected to a connecting member, which in turn is either detachably or permanently connected to the housing cover. In this case, the detachable connection between the connecting member and housing cover must be designed in accordance with the connection between the housing cover and the support body of the first variant.
As a result of the connection of the slide valve to the support body or the connecting member, the assembly comprised of the housing cover, the slide valve, and the support body or the connecting member can be separated so that less space is required for maintenance. This is advantageous in motor vehicles, for example, since therefore the liquid filter may also be positioned at locations which are less readily accessible.
One advantageous embodiment of the connection between the slide valve and the support body or the connecting member is a snap connection, which can be established as many times as desired. Furthermore, a snap connection is a connection which is simple and rapid to produce, and which may also be disconnected simply and rapidly.
A particularly advantageous embodiment of the snap connection comprises a spherical head which may be snapped into a corresponding socket. In this case, the spherical head may be positioned either on the slide valve or on the support body or connecting member. This embodiment has the advantage that the snap connection centers itself and may snap in during mounting when the slide valve is in any position or orientation relative to the support body or connecting member.
In a refinement of the liquid filter, the slide valve is attached to the housing body so as to be axially displaceable. In this case, the slide valve remains in the housing body during replacement of the filter element. The connection between the slide valve and the support body or connecting member is released, so that the housing cover and the support body or connecting member form a relatively short unit, which may be removed from the housing body in a small space. The slide valve may, for example, be locked in the housing body by a catch, due to which it is easy to install but cannot be removed non-destructively after installation. All components of the slide valve, such as the snap connection, sealing surfaces, or gaskets, are designed as components which are good for the service life of the valve, so that no maintenance is necessary. In this way, damage to the sealing surfaces of the slide valve, for example, may be avoided.
It is advantageous if the slide valve has a centering region, which is guided in the housing body. Because of this, the slide valve cannot tilt and cause a leakage flow. Furthermore, the slide valve remains in its position after separation from the support body and/or connecting member, due to which this connection may be produced again easily. The centering region may, for example, be formed by three ribs, which are supported against the housing body and do not impede drainage of the liquid into the liquid outlet. Furthermore, the centering region may also be constructed as a perforated disk, which is also permeable to the liquid.
In one advantageous embodiment of the present invention, the centering region is guided in the housing body in such a way that the slide valve is held by a clamping force during filter replacement. Because of this, the slide valve remains in its disengaged final position, in which the liquid may drain.
In accordance with a further embodiment of the present invention, the slide valve has two sealing regions, the filtered liquid area being separated from the filter outlet by the first sealing region and the unfiltered liquid inlet being separated from the filter outlet by the second sealing region. It is advantageous in this case if, when the liquid filter is opened, the second sealing region first opens the unfiltered liquid area to the filter outlet, so that the contaminated liquid may drain first. As the liquid filter is opened further, the slide valve is displaced further, so that the filtered liquid may also drain into the filter outlet. In this way, nearly all of the liquid may drain out of the liquid filter when the filter element is to be changed.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either alone or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.